TM 10-5411-232-13&P CARGO BED COVER (CBC) M105A2 TRAILER, TYPE II 0021 00 MAINTENANCE ALLOCATION CHART (MAC) INTRODUCTION The Army Maintenance System MAC This introduction provides a general explanation of all maintenance and repair functions authorized at various maintenance levels under the standard Army Maintenance System concept. The MAC (immediately following the introduction) designates overall authority and responsibility for the performance of maintenance functions on the identified end item or component.  The application of the maintenance functions to the end item or component shall be consistent with the capacities and capabilities of the designated maintenance levels, which are shown on the MAC in column (4) as: Unit - includes two subcolumns, C (operator/crew) and O (unit) maintenance. Direct Support - includes an F subcolumn. General Support - includes an H subcolumn. Depot - includes a D subcolumn. The tools and test equipment requirements (immediately following the MAC) list the tools and test equipment (both special tools and common tool sets) required for each maintenance function as referenced from the MAC. The remarks (immediately following the tools and test equipment requirements) contain supplemental instructions and explanatory notes for a particular maintenance function. Maintenance Functions Maintenance functions are limited to and are defined as follows: 1.    Inspect.  To determine the serviceability of an item by comparing its physical, mechanical, and/or electrical characteristics with established standards through examination (e.g., by sight, sound, or feel.) 2.    Test.  To verify serviceability by measuring the mechanical, pneumatic, hydraulic, or electrical characteristics of an item and comparing those characteristics with prescribed standards. 3.    Service.  Operations required periodically to keep an item in proper operating condition, i.e. to clean (includes decontaminate, when required), to preserve, to drain, to paint, or to replenish fuel, lubricants, chemical fluids, or gases. 4.    Adjust.  To maintain or regulate, within prescribed limits, by bringing into proper position, or by setting the operating characteristics to specified parameters. 5.    Align.  To adjust specified variable elements of an item to bring about optimum or desired performance. 0021 00-1